The present application relates to a lateral heterojunction bipolar transistor (HBT) structure, and particularly to a lateral heterojunction bipolar transistor (HBT) including a wide band gap emitter/collector which are epitaxially grown and to methods of manufacturing the same.
Heterojunction bipolar transistors (HBTs) include a heterojunction, i.e., a junction of two semiconductor materials having different band gaps, which coincide with a p-n junction between the base and the emitter. The wider band gap of the emitter relative to the band gap of the base in an HBT increases the current gain relative to a bipolar junction transistor employing a same semiconductor material across the base and the emitter and having similar physical dimensions and doping profiles for the base and emitter.
However, there can be difficulties associated with the manufacturing of the HBTs. For instance, in circuit applications, designers want the ability of having a metal contact to the emitter conveniently located so that it can be connected to the metal wire for the emitter, and the metal contact to the collector conveniently located so that it can be connected to the metal wire for the collector. However, with conventional methods for manufacturing an HBT, there may be design limitations in connection with how far the metal contact for the emitter may be placed in relation to the intrinsic base and how far the metal contact for the collector may be placed in relation to the intrinsic base because the horizontal emitter/collector area formed in the trench isolation structure is typically too small to place the metal contacts arbitrarily away from the intrinsic base which, in turn, may leave limited manufacturing choices. In other words, the ability to epitaxially grow the emitter and the collector such that they horizontally fill up a trench isolation structure in conventional processes may be limited to horizontally filling only small trenches having widths no greater than 20 nm. Moreover, due also to the relatively small size of the horizontal emitter/collector area, the ability to electrical probe the emitter, the collector, and intrinsic base for testing the device may also be difficult.